This invention relates to a floating (flying) magnetic head for a magnetic recording device used in a computer or the like which magnetic head converts magnetic signals into electric signals and vice versa to input and output the signals.
In order to achieve a high-density recording, various techniques have been introduced into magnetic recording devices serving as an external memory device. Magnetic heads used in the magnetic recording device have also been required to have a high performance to achieve high-density recording and reproduction. In order to meet the high-density recording requirement, an electromagnetic transducer element serving to effect the recording and reproduction has been constructed to have a narrow track design.
In the case of an advanced form of such narrow track design, the element is required to have electromagnetic transduction characteristics of high efficiency, and in order to enhance this transduction efficiency, the material for the element has been formed into a monocrystal structure. A typical example of such monocrystal material used as the electromagnetic transducer element is MnZn ferrite.
To determine the high performance of the element, a change in permeability has been discussed with respect to the relation between anistoropy energy and magnetostriction of a magnetic material, for example, by Magate et al (Technical Research Report 83 (1983) 11 by Institute of Electronics and Communication Engineers of Japan). Namely, the material of a high permeability is needed for the electromagnetic transducer element of a high efficiency.
The magnetostriction phenomenon of monocrystal materials has been discussed, for example, by Aso et al (IEEE Transactions on Magnetics 14 (1978) 76). According to the results of this discussion, the permeability of the monocrystal material is represented as a function of the magnetostriction through the induced magnetic anisotropy; however, attention is directed not to the values of the linear magneto-strictions possessed respectively by the individual materials, but to the effect of the saturation magnetostriction, and any detailed analysis of the linear magnetostriction constant with respect to the crystal orientation is not made.
One example of electromagnetic transducer element using such a monocrystal magnetic material is disclosed in Japanese Patent Unexamined Publication No. 57-55522. The greatest advantage of using the monocrystal material in the electromagnetic transducer element is that a high reproduction output can be obtained. Based on the results of the above discussions by Nagata et al and Aso et al, by controlling the value of the magnetostriction, the induced magnetic anisotropy energy is kept to within a predetermined range to cause the monocrystal magnetic material to have a high permeability, and further in the above techniques, by selecting a specified crystal orientation, the induced magnetic anisotropy energy is effectively controlled to successfully achieve the magnetic head of a high performance.
In the above techniques, it is necessary to control the magnetic anisotropy in order to obtain the element of a high conversion efficiency, and the magnetostriction phenomenon causing the induced magnetic anisotropy is utilized for this purpose. The selection of the crystal orientation of the monocrystal material is utilized as means for controlling the induced magnetic anisotropy in accordance with a change in the magnetostriction.
However, the magnetostriction phenomenon not only changes the magnetic characteristics of the magnetic material, but also causes a dynamic change with respect to the shape and etc., of the material. And besides, with a higher-density magnetic recording, technical problems which are inherent to the floating magnetic head and which have not so far been considered have arisen.
A floating magnetic head, used in an external magnetic recording device for a computer, effects the recording and reproduction by means of a single electromagnetic transducer element. Therefore, at the time of recording of signals, large electric current flows through an induction coil for exciting the element to greatly change the magnetization condition within the element, and the magnetic material whose magnetostriction is not zero is changed in shape due to a change in the magnetization condition of the interior of the magnetic material.
As a result, the element repeatedly expands and contracts in accordance with the change in the recording current, and therefore vibrates. On the other hand, in order to determine a track position for effecting the recording and reproduction, the magnetic head need to have information on the track position of the recording medium, and in order to achieve this, the magnetic head need to instantaneously effect the reproduction of a track servo signal. However, even after the signal is switched, the above vibration in the process of attenuation still remains, and when both the recording of signal and the track position change are effected successively, many and large noises are produced in the reproduction signal under the influence of the above vibration.
Such noises adversely affect the reproduction of the track position signal, and this results in a problem that the magnetic head fails to properly operate. This problem is conspicuous in the magnetic head using the monocrystal magnetic material for the electromagnetic transducer element.
The monocrystal has a high crystalline order, and therefore has a good nature, and is used as a high-performance material in various fields such as mechanical, magnetic and optical fields. The high crystalline order is determined by the degree of symmetry of the unit lattices constituting the whole of the crystal material, and the monocrystal has a low degree of symmetry, and is anisotropic. The anisotropy of the monocrystal may be an important factor in enhancing the performance, depending on its application or use; however, since other properties are also anisotropic, it is difficult to control them. It is thought that the vibration of the magnetic head which must be dealt with is caused by the anisotropy of the magnetostriction of the monocrystal.
In order to overcome the above problems, it can be considered to use an isotropic polycrystal magnetic material with a low crystalline order for the element. However, when the narrower-tack and higher-frequency design is adopted to achieve a high-density recording, the reproduction output is insufficient in the case of the polycrystal material, and besides noises are produced because of the low crystalline order. Therefore, the use of the monocrystal material is needed. Therefore, the technical problem to be solved is to reduce the vibration as much as possible.